Various curable resin compositions that can be cured by light (hereinafter referred to as photocurable resin compositions) (e.g., ultraviolet-curable resin compositions) have been used in inks, coating materials, adhesives, photoresists, and other applications. The photocurable resin compositions are highly valued since, for example, the photocurable resin compositions can be cured in a short time because of the high cure rate; the photocurable resin compositions are environment-compatible because of no use of solvents; and the photocurable resin compositions can save resources and energy.
A high-pressure mercury lamp, a xenon lamp, or the like, which has a relatively high irradiation intensity, is used as a light source for curing the photocurable resin composition. Mercury or rare elements are used for the light sources, and the light sources damage the environment. In recent years, a light emitting diode has been used as a light source with a low environmental load. The light emitting diode has, however, weak irradiation intensity and it is difficult to cure the photocurable resin sufficiently. Thus, the use of the light emitting diode causes insufficient surface curing and insufficient deep curing. Patent Documents 1 and 2 propose methods to solve the above-mentioned problems caused by using the light source having weak irradiation intensity. Patent Document 1 propose to use an isocyanurate derivative having a specific structure and Patent Document 2 propose to use a polymer produced by polymerizing a specific compound, to improve the deep curability of the photocurable resin composition.